Computer Keels and Fairing a Keel

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fxalbert
Posts: 58
Joined: Fri Mar 21, 2014 9:10 am

Computer Keels and Fairing a Keel

Post by fxalbert »

Has anyone tried using the Computer Keels templates for fairing their keels?
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Vento Solare
Posts: 356
Joined: Wed Dec 31, 1969 8:00 pm
Location: Newport, RI

Re: Computer Keels and Fairing a Keel

Post by Vento Solare »

I used them previously on my J/30. I bought the mylar prints from Compukeel and made my own templates. Unlike the J/109, the J/30 keels got "fatter" as the lead was cast in later boats. I used a power plane to get the shape to meet the templates and faired it. There was a noticeable difference in pointing after the keel was done.
JohnGreifzu
Posts: 47
Joined: Tue Oct 13, 2015 12:15 pm

Re: Computer Keels and Fairing a Keel

Post by JohnGreifzu »

We are currently in the process of doing this project with Hull 261! Happy to chat offline. johngreifzu@gmail.com

When done, I will post something in this forum.
carlbraden
Posts: 39
Joined: Sun Dec 07, 2014 9:18 pm

Re: Computer Keels and Fairing a Keel

Post by carlbraden »

John - I look forward to your results.
Regards
Carl
JohnGreifzu
Posts: 47
Joined: Tue Oct 13, 2015 12:15 pm

Re: Computer Keels and Fairing a Keel

Post by JohnGreifzu »

Part 1 - History and Getting Started

The keel on #261 has been a headache every off season I have owned the boat. We have had groundings, electrolysis, a lightning strike that seemed to damage the keel, canals of water at the seam, etc. (See pics below). Every year I sanded the problems, filled them with epoxy and faired them in myself. But I was only guessing on the right shape.

This winter we took the plunge and purchased the ComputerKeel templates to get the keel back in proper shape. The templates are made to class rule requirements. I opted to order the mylars only and build the templates myself. ComputerKeels provides detailed instructions on how to build the structure and cut them properly. It takes about $60 in supplies from Michaels and Home Depot. (Last pic below is the completed templates).

Grounding Damage:
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Post-lightning strike:
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Electrolysis:
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Canal:
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20201120_152357.jpg (347.76 KiB) Viewed 181 times
Templates:
IMG_0936.jpg
IMG_0936.jpg (1.25 MiB) Viewed 181 times
JohnGreifzu
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Re: Computer Keels and Fairing a Keel

Post by JohnGreifzu »

Part 2 - Paint Removal and Sanding

We are also in the process of redoing the bottom paint, so we used Total Boat Total Strip to remove paint when the temperatures were above 60 degrees. Then we had to switch to just sanding. With all the bottom paint removed we put the templates on the keel at the levels specified in the ComputerKeel instructions. The templates showed us where the keel was too fat. So we sanded those areas with a random orbital sander and 80 grit paper until the templates fit on the keel. Then we used a larger sanding block to "longboard" the remaining high areas.

Paint Removal:
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Template Placing:
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IMG_0970.jpg (1.24 MiB) Viewed 179 times
Sanding the High Spots:
IMG_1477.jpg
IMG_1477.jpg (1.07 MiB) Viewed 179 times
JohnGreifzu
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Joined: Tue Oct 13, 2015 12:15 pm

Re: Computer Keels and Fairing a Keel

Post by JohnGreifzu »

Part 3 - Fairing it Back and Sanding

After the templates fit on the keel, we applied thin layers of epoxy to even everything out. And then sanded again. Stay tuned for Part 4 with the finishing touches and painting ...

Epoxy and sand:
IMG_1005.jpg
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IMG_1004.jpg
IMG_1004.jpg (1.11 MiB) Viewed 178 times
Last edited by JohnGreifzu on Thu Dec 22, 2022 3:44 pm, edited 1 time in total.
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Vento Solare
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Re: Computer Keels and Fairing a Keel

Post by Vento Solare »

Great project John. Here is a tip to keep the keel better encapsulated so the barrier coat sticks. Once you are down to the stripped lead with the basic shape before using any fairing compound do the following.
  • Have a few stiff long bristle wire brushes handy - these will get destroyed in the process. Also have a few 4 inch or wider brushes with bristles that won't fall out (e.g. not a chip brush)
  • Use a wire brush to scuff the lead and make sure shiny material is exposed. The lead will oxidize quickly so only work with a manageable area, or do it with two people so the steps can go quickly
  • mix a batch of neat epoxy and paint the neat epoxy over the scuffed area
  • Immediately take a wire brush and work it into the scuffed area
  • after working the epoxy into the area, use another brush wet with neat epoxy to smooth the surface
  • repeat as necessary until the entire keel is done
  • let this kick, then rinse with water to remove any amine blush
  • light sand by hand with 80 grit paper to provide a surface for the faring compound and barrier coat will adhere to
The prep above will help ensure your fairing work doesn't separate from the lead.
JohnGreifzu
Posts: 47
Joined: Tue Oct 13, 2015 12:15 pm

Re: Computer Keels and Fairing a Keel

Post by JohnGreifzu »

Thanks, Bill. We did not do that. So, I will tell you a year from now if we lose any adherence ...
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